Hmm its odd that some think that just because you have giants every door has to be able to accomodate them. Why not have areas that giant races cannot enter due to there size, a penalty if you wish for being as large (and as often as not stronger) as the other races. Gives players a little bit of mystery to there race, after all what do dwarves get up to behind there small doors. And what?, do dwarves wonder do kran get up to up those overly large stairs (with steps to tall for a dwarf to easily climb up)...
Gamebalance and racial balance and class balance is the death of all good games, differance is and often even wild difference is the key to getting the old imagination going and making things fresh. What a player cant see fully they will think and speculate about, speculation becomes wonder, wonder becomes rumor, rumor becomes myth and myth creates action (with a good niggling thought of a asentive(?) behind the wall), adventure is to find and search for the unknown and if all is known to all then there is no adventure is there.
nurse?... ill take my medication now.